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<title>WebGL Uninitialized GL Resources Tests</title>
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description("Tests to check user code cannot access uninitialized data from GL resources.");

var wtu = WebGLTestUtils;
var gl = wtu.create3DContext("canvas");
if (!gl)
  testFailed("Context created.");
else
  testPassed("Context created.");

function setupTexture(texWidth, texHeight) {
    var texture = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_2D, texture);
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, texWidth, texHeight, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);

    // this can be quite undeterministic so to improve odds of seeing uninitialized data write bits
    // into tex then delete texture then re-create one with same characteristics (driver will likely reuse mem)
    // with this trick on r59046 WebKit/OSX I get FAIL 100% of the time instead of ~15% of the time.

    var badData = new Uint8Array(texWidth * texHeight * 4);
    for (var i = 0; i < badData.length; ++i)
        badData[i] = i % 255;

    gl.texSubImage2D(gl.TEXTURE_2D, 0, 0, 0, texWidth, texHeight, gl.RGBA, gl.UNSIGNED_BYTE, badData);
    gl.finish(); // make sure it has been uploaded

    gl.deleteTexture(texture);
    gl.finish(); // make sure it has been deleted

    var texture = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_2D, texture);
    return texture;
}

function checkNonZeroPixels(texture, texWidth, texHeight, skipX, skipY, skipWidth, skipHeight, skipR, skipG, skipB, skipA) {
    gl.bindTexture(gl.TEXTURE_2D, null);
    var fb = gl.createFramebuffer();
    gl.bindFramebuffer(gl.FRAMEBUFFER, fb);
    gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0);
    shouldBe("gl.checkFramebufferStatus(gl.FRAMEBUFFER)", "gl.FRAMEBUFFER_COMPLETE");

    var data = new Uint8Array(texWidth * texHeight * 4);
    gl.readPixels(0, 0, texWidth, texHeight, gl.RGBA, gl.UNSIGNED_BYTE, data);

    var k = 0;
    for (var y = 0; y < texHeight; ++y) {
        for (var x = 0; x < texWidth; ++x) {
            var index = (y * texWidth + x) * 4;
            if (x >= skipX && x < skipX + skipWidth && y >= skipY && y < skipY + skipHeight) {
                if (data[index] != skipR || data[index + 1] != skipG || data[index + 2] != skipB || data[index + 3] != skipA) {
                    testFailed("non-zero pixel values are wrong");
                    return;
                }
            } else {
                for (var i = 0; i < 4; ++i) {
                    if (data[index + i] != 0)
                        k++;
                }
            }
        }
    }
    if (k) {
        testFailed("Found " + k + " non-zero bytes");
    } else {
        testPassed("All data initialized");
    }
}

var width = 512;
var height = 512;

debug("");
debug("Reading an uninitialized texture (texImage2D) should succeed with all bytes set to 0.");

var tex = setupTexture(width, height);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
checkNonZeroPixels(tex, width, height, 0, 0, 0, 0, 0, 0, 0, 0);
gl.deleteTexture(tex);
gl.finish();
glErrorShouldBe(gl, gl.NO_ERROR);

debug("");
debug("Reading an uninitialized portion of a texture (copyTexImage2D) should succeed with all bytes set to 0.");

var tex = setupTexture(width, height);
var fbo = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
var rbo = gl.createRenderbuffer();
gl.bindRenderbuffer(gl.RENDERBUFFER, rbo);
var fboWidth = 16;
var fboHeight = 16;
gl.renderbufferStorage(gl.RENDERBUFFER, gl.RGBA4, fboWidth, fboHeight);
gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.RENDERBUFFER, rbo);
shouldBe("gl.checkFramebufferStatus(gl.FRAMEBUFFER)", "gl.FRAMEBUFFER_COMPLETE");
gl.clearColor(1.0, 0.0, 0.0, 1.0);
gl.clear(gl.COLOR_BUFFER_BIT);
glErrorShouldBe(gl, gl.NO_ERROR);
gl.copyTexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, 0, 0, width, height, 0);
checkNonZeroPixels(tex, width, height, 0, 0, fboWidth, fboHeight, 255, 0, 0, 255);
gl.deleteTexture(tex);
gl.finish();
glErrorShouldBe(gl, gl.NO_ERROR);

debug("");
debug("Reading an uninitialized portion of a texture (copyTexImage2D with negative x and y) should succeed with all bytes set to 0.");

var tex = setupTexture(width, height);
var fbo = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
var rbo = gl.createRenderbuffer();
gl.bindRenderbuffer(gl.RENDERBUFFER, rbo);
var fboWidth = 16;
var fboHeight = 16;
gl.renderbufferStorage(gl.RENDERBUFFER, gl.RGBA4, fboWidth, fboHeight);
gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.RENDERBUFFER, rbo);
shouldBe("gl.checkFramebufferStatus(gl.FRAMEBUFFER)", "gl.FRAMEBUFFER_COMPLETE");
gl.clearColor(1.0, 0.0, 0.0, 1.0);
gl.clear(gl.COLOR_BUFFER_BIT);
glErrorShouldBe(gl, gl.NO_ERROR);
var x = -8;
var y = -8;
gl.copyTexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, x, y, width, height, 0);
checkNonZeroPixels(tex, width, height, -x, -y, fboWidth, fboHeight, 255, 0, 0, 255);
gl.deleteTexture(tex);
gl.finish();
glErrorShouldBe(gl, gl.NO_ERROR);

debug("");
debug("Reading an uninitialized portion of a texture (copyTexImage2D from WebGL internal fbo) should succeed with all bytes set to 0.");

var tex = setupTexture(width, height);
gl.bindFramebuffer(gl.FRAMEBUFFER, null);
gl.clearColor(0.0, 1.0, 0.0, 0.0);
gl.clear(gl.COLOR_BUFFER_BIT);
glErrorShouldBe(gl, gl.NO_ERROR);
gl.copyTexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, 0, 0, width, height, 0);
checkNonZeroPixels(tex, width, height, 0, 0, gl.canvas.width, gl.canvas.height, 0, 255, 0, 0);
gl.deleteTexture(tex);
gl.finish();
glErrorShouldBe(gl, gl.NO_ERROR);

//TODO: uninitialized vertex array buffer
//TODO: uninitialized vertex elements buffer
//TODO: uninitialized framebuffer? (implementations would need to do a GL clear at first binding?)
//TODO: uninitialized renderbuffer? (implementations would need to do a GL clear at first binding?)
//TODO: uninitialized uniform arrays?

debug("");
successfullyParsed = true;
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